In April 2020, we entered into a purchase agreement for the sale of an aggregate of $1.0 billion principal amount of senior convertible notes (the “2025 Notes”) in a private offering to qualified institutional buyers pursuant to Rule 144A under the Securities Act of 1933, as amended (the “Securities Act”). The 2025 Notes consisted of an $850.0 million initial placement and an over-allotment option that provided the initial purchasers of the 2025 Notes with the option to purchase an additional $150.0 million aggregate principal amount of the 2025 Notes, which was fully exercised. The 2025 Notes were issued pursuant to an Indenture dated April 28, 2020 (the “Indenture”). The net proceeds from the issuance of the 2025 Notes were $888.6 million, net of debt issuance costs and cash used to purchase the capped call transactions (the “2025 Capped Call Transactions”) discussed below. The debt issuance costs are amortized to interest expense using the effective interest rate method.

The 2025 Notes are unsecured and unsubordinated obligations. Interest is payable in cash semi-annually in arrears beginning on November 1, 2020 at a rate of 0.25% per year. The 2025 Notes mature on May 1, 2025 unless repurchased, redeemed, or converted in accordance with the terms prior to such date.

The 2025 Notes are convertible into cash, shares of our Class A common stock, or a combination of cash and shares of our Class A common stock, at our election, at an initial conversion rate of 46.1233 shares of Class A common stock per $1,000 principal amount of 2025 Notes, which is equivalent to an initial conversion price of approximately $21.68 (the “2025 Conversion Price”) per share of our Class A common stock. We may redeem for cash all or portions of the 2025 Notes, at our option, on or after May 6, 2023 based on certain circumstances.

In August 2019, we entered into a purchase agreement for the sale of an aggregate of $1.265 billion principal amount of senior convertible notes (the “2026 Notes”) in a private offering to qualified institutional buyers pursuant to Rule 144A under the Securities Act. The net proceeds from the issuance of the 2026 Notes were $1.15 billion, net of debt issuance costs and cash used to purchase the capped call transactions (the “2026 Capped Call Transactions”) discussed below. The debt issuance costs are amortized to interest expense using the effective interest rate method.

The 2026 Notes are unsecured and unsubordinated obligations. Interest is payable in cash semi-annually in arrears beginning on February 1, 2020 at a rate of 0.75% per year. The 2026 Notes mature on August 1, 2026 unless repurchased, redeemed, or converted in accordance with the terms prior to such date.

The 2026 Notes are convertible into cash, shares of our Class A common stock, or a combination of cash and shares of our Class A common stock, at our election, at an initial conversion rate of 43.8481 shares of Class A common stock per $1,000 principal amount of 2026 Notes, which is equivalent to an initial conversion price of approximately $22.81 (the “2026 Conversion Price”) per share of our Class A common stock. We may redeem for cash all or portions of the 2026 Notes, at our option, on or after August 6, 2023 based on certain circumstances.

	As of March 31, 2021
	2025 Notes			2026 Notes
	(in thousands)
Principal	$	1,000,000		$	1,265,000
Unamortized debt issuance costs		(9,330	)		(10,467	)
Net carrying amount	$	990,670		$	1,254,533

As of March 31, 2021, the debt issuance costs on the 2025 Notes and 2026 Notes will be amortized over the remaining period of approximately 4.1 years and 5.3 years, respectively.

Prior to January 1, 2021, we separated the 2025 Notes and 2026 Notes into liability and equity components. On issuance, the carrying amount of the equity components was recorded as a debt discount and subsequently amortized to interest expense. Effective January 1, 2021, we early adopted ASU 2020-06 using the modified retrospective approach. The 2025 Notes and 2026 Notes are each accounted for as a single liability measured at its amortized cost, as no other embedded features require bifurcation and recognition as derivatives. Adoption of the new standard resulted in a decrease to accumulated deficit of $95.0 million, a decrease to additional paid-in capital of $664.0 million, and an increase to convertible senior notes, net of $569.0 million.

Interest expense related to the amortization of debt issuance costs was $1.0 million for the three months ended March 31, 2021. Interest expense related to the amortization of debt discount and issuance costs was $11.6 million for the three months ended March 31, 2020, while contractual interest expense was $3.0 million and $2.4 million for the three months ended March 31, 2021 and 2020, respectively.

As of March 31, 2021, the if-converted value of the 2025 Notes and 2026 Notes exceeded the principal amount by $1.4 billion and $1.6 billion, respectively. The sale price for conversion was satisfied as of March 31, 2021 and as a result, the Convertible Notes will continue to be eligible for optional conversion during the second quarter of 2021.

Refer to our audited consolidated financial statements and Note 7 in the Annual Report for additional details.

In connection with the pricing of the 2025 Notes and 2026 Notes, we entered into the 2025 Capped Call Transactions and the 2026 Capped Call Transactions (together, the “Capped Call Transactions”), respectively, with certain counterparties at a net cost of $100.0 million and $102.1 million, respectively. The cap price of the 2025 Capped Call Transactions is initially $32.12 per share of our Class A common stock and the cap price of the 2026 Capped Call Transaction is $32.58 per share of our Class A common stock. Both are subject to certain adjustments under the terms of the Capped Call Transactions. Conditions that cause adjustments to the initial strike price of the Capped Call Transactions mirror conditions that result in corresponding adjustments for the Convertible Notes.

The Capped Call Transactions are intended to reduce potential dilution to holders of our Class A common stock beyond the conversion prices up to the cap prices on any conversion of the Convertible Notes or offset any cash payments we are required to make in excess of the principal amount, as the case may be, with such reduction or offset subject to a cap. The cost of the Capped Call Transactions was recorded as a reduction of our additional paid-in capital in our consolidated balance sheets. As of March 31, 2021, the Capped Call Transactions were in-the-money and will not be remeasured as long as they continue to meet the conditions for equity classification.